Stainless Steel 301 Constant Force Spring, 0.005" Thick, 0.42" ID, 0.75 Lb. Load

Constant Force Spring is a roll of pre-stressed Type 301 Stainless Steel strip which exerts a nearly constant restraining force to resist uncoiling. When the strip is extended, the inherent stress resists the loading force at a nearly constant rate. In use, the spring is usually mounted by tightly wrapping it on a drum. The free end is then attached to the loading force such as in a counterbalance application. This relationship can also be reversed. Typical applications include brush springs for motors, counterbalance springs for window sashes, and carriage return springs for typewriters. If the spring is mounted on a drum, the drum diameter should be 10 to 20 percent larger than its natural diameter. One and one-half wraps should remain on the drum at maximum extension. The strip becomes unstable at long extensions and should be guided to prevent twisting or kinking on recoil. Idler pulleys must be larger in diameter than the natural diameter and should never be used to cause back-bending against the natural radius of curvature.